
Samsung Galaxy S SL
The latest firmware for Samsung Galaxy S SL (GT-I9003) is I9003XWLF3 with Android 2.3.6 (Gingerbread), released on June 27, 2012 for 1 region (CSC). Every official firmware build for GT-I9003, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/I9003XWLF3
All 10 builds in our database run Android 2.3.6 (Gingerbread). The newest build, I9003XWLF3, was released on June 27, 2012. No new build has appeared for 174 months, so regular updates for this model have most likely ended.
Box codes of GT-I9003 for different colors and markets. Firmware is chosen by the model code GT-I9003 and your region (CSC), not by the SKU.

GT-I9308

GT-I9268

GT-I9228

GT-I9210

GT-I9108

GT-I9103

GT-I9100T

GT-I9050
The newest firmware for GT-I9003 runs Android 2.3.6 (Gingerbread): build I9003XWLF3, released on June 27, 2012.
The latest build for GT-I9003, I9003XWLF3, was released on June 27, 2012 (14 years ago).
GT-I9003 has had no new firmware for 174 months, so regular updates have most likely ended.
Yes, all firmware files for GT-I9003 are 100% official, original, and obtained directly from Samsung servers.
To flash GT-I9003, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing GT-I9003.